Hi,
Nice to meet you, welcome on the forum.
To build a recent image for your device(s) follow this Wiki.
For your rock64 device
sudo buildarmimg -d rock64 -e kde-plasma -v 2025.02.02 -b unstable n
To add or remove some packages modify this file (choose your desktop environment here)
/usr/share/manjaro-arm-tools/profiles/arm-profiles/editions/
Find the build image here
/var/cache/manjaro-arm-tools/img/
Enjoy !